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Objective-C iOS Development for Legacy & Enterprise Apps · Lesson

Handling Nullability and Type Mapping Across the Bridge

Clean Objective-C and Swift interop depends on precise nullability annotations and correct type mapping. This lesson shows how to annotate headers so Swift sees safe, idiomatic APIs.

Why Nullability Matters

Without annotations, Swift imports every Objective-C pointer as an implicitly unwrapped optional. That hides crashes and produces ugly Swift APIs.

The Three Annotations

Objective-C offers three nullability keywords:

  • nonnull imports as a plain type
  • nullable imports as an optional
  • null_unspecified imports as implicitly unwrapped

All lessons in this course

  1. Bridging Objective-C to Swift
  2. Bridging Swift to Objective-C
  3. Creating Objective-C Frameworks
  4. Handling Nullability and Type Mapping Across the Bridge
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